Using copied data in a distributed storage network

ABSTRACT

A storage unit includes an interface configured to interface and communicate with a dispersed storage network (DSN), a memory that stores operational instructions, and processing circuitry. The storage unit receives a set of read slice requests for a set of encoded data slices (EDSs) associated with a data object stored within a first set of storage units, where the storage the first set of storage units includes the storage unit. When at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units, the storage unit identifies at least one EDS associated with a data object that is stored in a second set of storage units, obtains the at least one EDS and stores the at least one EDS in the storage unit.

CROSS REFERENCE TO RELATED PATENTS

The present U.S. Utility Patent application claims priority pursuant to35 U.S.C. § 120, as a continuation of U.S. Utility application Ser. No.16/724,430, entitled “FACILITATION OF TEMPORARY STORAGE OF A SLICE IN ASTORAGE UNIT (SU)”, filed Dec. 23, 2019, which is a continuation of U.S.Utility patent application Ser. No. 15/837,455, entitled “TEMPORARILYSTORING DROPPED AND REBUILT SLICES IN A DSN MEMORY,” filed Dec. 11,2017, issued as U.S. Pat. No. 10,521,298 on Dec. 31, 2019, which is acontinuation-in-part (CIP) of U.S. Utility patent application Ser. No.15/642,875, entitled “PRIORITIZED DATA REBUILDING IN A DISPERSED STORAGENETWORK,” filed Jul. 6, 2017, issued as U.S. Pat. No. 10,120,739 on Nov.6, 2018, which claims priority pursuant to 35 U.S.C. § 120, as acontinuation-in-part (CIP) of U.S. Utility patent application Ser. No.14/869,240, entitled “COORDINATING STORAGE OF DATA IN DISPERSED STORAGENETWORKS,” filed Sep. 29, 2015, issued as U.S. Pat. No. 9,727,275 onAug. 8, 2017, which claims priority pursuant to 35 U.S.C. § 119(e) toU.S. Provisional Application No. 62/086,542, entitled “CONSISTENTSTORAGE OF DATA IN A DISPERSED STORAGE NETWORK,” filed Dec. 2, 2014, allof which are hereby incorporated herein by reference in their entiretyand made part of the present U.S. Utility Patent Application for allpurposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

Within prior art data storage systems, sometimes storage processes lessthan fully unsuccessful. When unsuccessful, the prior art does notprovide adequate and acceptable means by which unsuccessful storageattempts and processes may be made successful. There exists room forimprovement within prior art data storage systems regarding the mannerby which data storage processes may be performed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of another embodiment of a dispersedor distributed storage network (DSN) in accordance with the presentinvention;

FIG. 10 is a flowchart illustrating an example of storing data inaccordance with the present invention; and

FIG. 11 is a diagram illustrating an embodiment of a method forexecution by one or more computing devices in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2 , or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each of the managing unit 18 and the integrity processing unit20 may be separate computing devices, may be a common computing device,and/or may be integrated into one or more of the computing devices 12-16and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 & 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data as subsequently described with reference to oneor more of FIGS. 3-8 . In this example embodiment, computing device 16functions as a dispersed storage processing agent for computing device14. In this role, computing device 16 dispersed storage error encodesand decodes data on behalf of computing device 14. With the use ofdispersed storage error encoding and decoding, the DSN 10 is tolerant ofa significant number of storage unit failures (the number of failures isbased on parameters of the dispersed storage error encoding function)without loss of data and without the need for a redundant or backupcopies of the data. Further, the DSN 10 stores data for an indefiniteperiod of time without data loss and in a secure manner (e.g., thesystem is very resistant to unauthorized attempts at accessing thedata).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSN memory 22 fora user device, a group of devices, or for public access and establishesper vault dispersed storage (DS) error encoding parameters for a vault.The managing unit 18 facilitates storage of DS error encoding parametersfor each vault by updating registry information of the DSN 10, where theregistry information may be stored in the DSN memory 22, a computingdevice 12-16, the managing unit 18, and/or the integrity processing unit20.

The DSN managing unit 18 creates and stores user profile information(e.g., an access control list (ACL)) in local memory and/or withinmemory of the DSN module 22. The user profile information includesauthentication information, permissions, and/or the security parameters.The security parameters may include encryption/decryption scheme, one ormore encryption keys, key generation scheme, and/or dataencoding/decoding scheme.

The DSN managing unit 18 creates billing information for a particularuser, a user group, a vault access, public vault access, etc. Forinstance, the DSN managing unit 18 tracks the number of times a useraccesses a non-public vault and/or public vaults, which can be used togenerate a per-access billing information. In another instance, the DSNmanaging unit 18 tracks the amount of data stored and/or retrieved by auser device and/or a user group, which can be used to generate aper-data-amount billing information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an 10 interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1 . Note that the IOdevice interface module 62 and/or the memory interface modules 66-76 maybe collectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. The dispersed storage error encodingparameters include an encoding function (e.g., information dispersalalgorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding,non-systematic encoding, on-line codes, etc.), a data segmentingprotocol (e.g., data segment size, fixed, variable, etc.), and per datasegment encoding values. The per data segment encoding values include atotal, or pillar width, number (T) of encoded data slices per encodingof a data segment i.e., in a set of encoded data slices); a decodethreshold number (D) of encoded data slices of a set of encoded dataslices that are needed to recover the data segment; a read thresholdnumber (R) of encoded data slices to indicate a number of encoded dataslices per set to be read from storage for decoding of the data segment;and/or a write threshold number (W) to indicate a number of encoded dataslices per set that must be accurately stored before the encoded datasegment is deemed to have been properly stored. The dispersed storageerror encoding parameters may further include slicing information (e.g.,the number of encoded data slices that will be created for each datasegment) and/or slice security information (e.g., per encoded data sliceencryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5 ); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides the data(e.g., a file (e.g., text, video, audio, etc.), a data object, or otherdata arrangement) into a plurality of fixed sized data segments (e.g., 1through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more).The number of data segments created is dependent of the size of the dataand the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3 , the computing device alsocreates a slice name (SN) for each encoded data slice (EDS) in the setof encoded data slices. A typical format for a slice name 60 is shown inFIG. 6 . As shown, the slice name (SN) 60 includes a pillar number ofthe encoded data slice (e.g., one of 1-T), a data segment number (e.g.,one of 1-Y), a vault identifier (ID), a data object identifier (ID), andmay further include revision level information of the encoded dataslices. The slice name functions as, at least part of, a DSN address forthe encoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4 . In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG. 8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4 . The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

In some examples, note that dispersed or distributed storage network(DSN) memory includes one or more of a plurality of storage units (SUs)such as SUs 36 (e.g., that may alternatively be referred to adistributed storage and/or task network (DSTN) module that includes aplurality of distributed storage and/or task (DST) execution units 36that may be located at geographically different sites (e.g., one inChicago, one in Milwaukee, etc.). Each of the SUs (e.g., alternativelyreferred to as DST execution units in some examples) is operable tostore dispersed error encoded data and/or to execute, in a distributedmanner, one or more tasks on data. The tasks may be a simple function(e.g., a mathematical function, a logic function, an identify function,a find function, a search engine function, a replace function, etc.), acomplex function (e.g., compression, human and/or computer languagetranslation, text-to-voice conversion, voice-to-text conversion, etc.),multiple simple and/or complex functions, one or more algorithms, one ormore applications, etc.

FIG. 9 is a schematic block diagram of another embodiment 900 of adispersed or distributed storage network (DSN) in accordance with thepresent invention. This diagram includes a schematic block diagram ofanother embodiment of a DSN that includes a primary storage set (e.g., afirst SU set) 910, a temporary storage set (e.g., a second SU set) 910,the network 24 of FIG. 1 , and the computing device 16 of FIG. 1 . Theprimary storage set 910 includes a set of storage units (SUs) 1-n. Thetemporary storage set 920 includes another set of SUs B1-Bn. A number ofSUs of the primary storage set 910 may be different for the same as anumber of SUs of the temporary storage set 920. Each SU may beimplemented utilizing one or the SUs 36 of the DSN memory 22 of FIG. 1 .

The DSN functions to store data in one or more of the primary storageset 910 and the temporary storage set 920. In an example of operation ofthe storing of the data, the computing device 16 receives a store datarequest 901, where the store data request 901 includes one or more ofthe data, a data identifier, and a requesting entity identifier. Havingreceived the store data request 901, the computing device 16 dispersedstorage error encodes the data to produce a plurality of sets of encodeddata slices. Having produced the encoded data slices, the computingdevice 16 generates one or more sets of write slice requests, where theone or more sets of write slice requests includes the plurality of setsof encoded data slices.

Having produced the one or more sets of write slice request, thecomputing device 16 issues, via the network 24, the one or more writeslice requests to the SUs of the primary storage set 910. Each SUreceiving a write slice request and successfully storing an encoded dataslice, issues a write slice response, via the network 24, to thecomputing device 16 indicating that the encoded data slice has beensuccessfully stored. For example, the SU 1 issues a write slice response1 to the computing device 16, where the write slice response 1 indicatesthat an encoded data slice 1 has been successfully stored within the SU1.

The computing device 16 receives write slice responses from at leastsome of the SUs of the primary storage set 910. When the computingdevice 16 receives write slice responses indicating that at least awrite threshold number of encoded data slices have been successfullystored, the computing device 16 may detect a failure of storage of anencoded data slice associated with the storage error. The detectingincludes at least one of interpreting a received write slice responsethat indicates that the storage error and determining that a storagetimeframe has elapsed since issuing a write slice request withoutreceiving a corresponding write slice response. For example, thecomputing device 16 indicates that an encoded data slice 3 is an errorslice when the computing device 16 determines that the storage timeframeelapsed for storage of an encoded data slice 3 that was sent to the SU 3for storage, without receiving an indication that the encoded data slice3 was successfully stored.

Having determined the error slice, the computing device 16 determineswhether to temporarily store the encoded data slice. The determining maybe based on one or more of expected future availability of the SU 3associated with the error slice, a predetermination, a priority level,interpreting a request, interpreting a system registry entry, and therequesting entity identifier. For example, the computing device 16indicates to temporarily store the encoded data slice when the expectedfuture availability of the SU 3 is less than an availability thresholdlevel. As another example, the computing device 16 indicates totemporarily store the encoded data slice when an interpretation of thesystem registry indicates to temporarily store all detected error slicesassociated with a virtual storage vault affiliated with the requestingentity identifier.

When temporarily storing encoded data slice, the computing device 16dispersed storage error encodes the error slice to produce a set oftemporary encoded data slices. For example, the computing device 16dispersed storage error encodes encoded data slice 3 to producetemporary encoded data slices 3-1 through 3-n. Having produced the setof temporary encoded data slices, the computing device 16 facilitatesstorage of the set of temporary encoded data slices in SUs of thetemporary storage set 920. For example, the computing device 16 issues,via the network 24, a set of write temporary slice requests to SUs B1through Bn, where the set of write temporary slice requests includes theset of temporary encoded data slices 3-1 through 3-n.

Subsequent to storage of the set of temporary encoded data slices, thecomputing device 16 determines to re-store the error slice in theprimary set of SUs. The determining may be based on one or more ofdetecting that a weight timeframe has expired from a previous attempt,detecting that a SU error condition has subsided, favorable SUavailability is detected, receiving a recovery request for the errorslice, detecting that available capacity of the temporary storage set920 is less than a low threshold level, and detecting that an activityindicator indicates a level of activity that is lower than a lowthreshold level. Alternatively, or in addition to, a SU of the primarystorage set 910 determines to re-store the error slice in the primaryset of SUs.

Having determined to re-store the error slice in the primary set of SUs,the computing device 16 recovers the encoded data slice from thetemporary stored set. For example, the computing device 16 issues, viathe network 24, a set of read slice requests to the SUs B1-Bn, receivesread slice responses, and dispersed storage error decodes a decodethreshold number of received temporary encoded data slices to reproduceencoded data slice 3.

Having reproduced the error slice, the computing device 16 facilitatesstorage of the reproduced error slice in a primary storage set 910. Forexample, the computing device 16 issues, via the network 24, a writeslice request to SU 3, where the write slice request includes thereproduced encoded data slice 3.

In an example of operation and implementation, a computing device and/orstorage unit (SU) includes an interface configured to interface andcommunicate with a dispersed or distributed storage network (DSN), amemory that stores operational instructions, and a processing module,processor, and/or processing circuitry operably coupled to the interfaceand memory. The processing module, processor, and/or processingcircuitry is configured to execute the operational instructions toperform various operations, functions, etc. In some examples, theprocessing module, processor, and/or processing circuitry, when operablewithin the computing device and/or SU based on the operationalinstructions, is configured to perform various operations, functions,etc. in certain examples, the processing module, processor, and/orprocessing circuitry, when operable within the computing device and/orSU is configured to perform one or more functions that may includegeneration of one or more signals, processing of one or more signals,receiving of one or more signals, transmission of one or more signals,interpreting of one or more signals, etc. and/or any other operations asdescribed herein and/or their equivalents.

In an example of operation and implementation, the computing device 16is configured to issue a set of write requests to a first storage unit(SU) set (e.g., primary storage set 910) based on a set of encoded dataslices (EDSs) associated with a data object to be stored therein. Notethat the data object is segmented into a plurality of data segments, anda data segment of the plurality of data segments is dispersed errorencoded in accordance with dispersed error encoding parameters toproduce the set of EDSs. Also, note that a write threshold number ofEDSs provides for a successful transfer of the set of EDSs from a firstat least one location in the DSN to a second at least one location inthe DSN.

The computing device 16 is also configured to determine that the writethreshold number of EDSs and fewer than all of the set of EDSs have beensuccessfully stored within the first SUs set based on at least somewrite responses from at least some storage units (SUs) of the first SUset. The computing device 16 is also configured to determine to storetemporarily within a second SU set (e.g., temporary storage se) at leastone remaining EDS of the set of EDSs that has not been successfullystored within the first SUs set. The computing device 16 is alsoconfigured to facilitate temporary storage of the at least one remainingEDS of the set of EDSs within the second SU set. The computing device 16is also configured to recover the at least one remaining EDS from thetemporary storage within the second SU set. The computing device 16 isalso configured to issue at least one additional write request to thefirst SU set based on the at least one remaining EDS.

In some examples, the computing device 16 is also configured to receive(e.g., from a requesting entity such as another computing device, a SU,etc.) a store data request that includes the data object, a dataidentifier, and/or a requesting entity identifier. The computing device16 is also configured to dispersed error encode the data object inaccordance with the dispersed error encoding parameters to produce theset of EDSs.

In even other examples, the computing device 16 is also configureddetect at least one storage failure associated with the at least oneremaining EDS of the set of EDSs based on interpretation of at least onereceived write response that indicates a storage error and/ordetermination that a storage timeframe has elapsed since issuing atleast one of the set of write requests without receiving a correspondingwrite response.

Also, in certain examples, the computing device 16 is also configureddetermine to store temporarily within the second SU set at least oneremaining EDS of the set of EDSs that has not been successfully storedwithin the first SUs set based on expected future availability of atleast one SU of the first SU set, a predetermination, a priority level,interpretation of a request, interpretation of a system registry entry,a requesting entity identifier, an expected future availability of theat least one SU of the first SU set being less than an availabilitythreshold level, and/or interpretation of the system registry thatindicates to store temporarily at least one detected EDS error that isassociated with a virtual storage vault affiliated with the requestingentity identifier.

In some examples, with respect to a data object, the data object issegmented into a plurality of data segments, and a data segment of theplurality of data segments is dispersed error encoded in accordance withdispersed error encoding parameters to produce a set of encoded dataslices (EDSs). Such a set of EDSs are or may then be distributedlystored in a plurality of storage units (SUs) within the DSN (e.g., afirst SU set, a second SU set, and/or other SUs). In some examples, theset of EDSs is of pillar width. Also, with respect to certainimplementations, note that the decode threshold number of EDSs areneeded to recover the data segment, and a read threshold number of EDSsprovides for reconstruction of the data segment. Also, a write thresholdnumber of EDSs provides for a successful transfer of the set of EDSsfrom a first at least one location in the DSN to a second at least onelocation in the DSN. The set of EDSs is of pillar width and includes apillar number of EDSs. Also, in some examples, each of the decodethreshold, the read threshold, and the write threshold is less than thepillar number. Also, in some particular examples, the write thresholdnumber is greater than or equal to the read threshold number that isgreater than or equal to the decode threshold number.

Note that the computing device as described herein may be located at afirst premises that is remotely located from a second premisesassociated with at least one other SU, DS unit, computing device, atleast one SU of a plurality of SUs within the DSN (e.g., such as aplurality of SUs that are implemented to store distributedly the set ofEDSs, the first SU set, the second SU set, etc.), etc. In addition, notethat such a computing device as described herein may be implemented asany of a number of different devices including a managing unit that isremotely located from another SU, DS unit, computing device, etc. withinthe DSN and/or other device within the DSN, an integrity processing unitthat is remotely located from another computing device and/or otherdevice within the DSN, a scheduling unit that is remotely located fromanother computing device and/or SU within the DSN, and/or other device.Also, note that such a computing device as described herein may be ofany of a variety of types of devices as described herein and/or theirequivalents including a DS unit and/or SU included within any groupand/or set of DS units and/or SUs within the DSN, a wireless smartphone, a laptop, a tablet, a personal computers (PC), a work station,and/or a video game device. Also, note also that the DSN may beimplemented to include or be based on any of a number of different typesof communication systems including a wireless communication system, awire lined communication system, a non-public intranet system, a publicinternet system, a local area network (LAN), and/or a wide area network(WAN).

FIG. 10 is a flowchart illustrating an example 1000 of storing data inaccordance with the present invention. This diagram includes a flowchartillustrating an example of storing data. The method 1000 begins at astep 1010 where a processing module (e.g., of a distributed storage (DS)client module of a computing device such as computing device 16 of FIG.1 ) issues a set of write slice requests to SUs of a primary set of SUs.For example, the processing module dispersed storage error encodes datato produce a plurality of sets of encoded data slices, generates the setof write slice requests to include one or more sets of encoded dataslices of the plurality of sets of encoded data slices, and sends theset of write slice requests to the set of SUs of the primary set of SUs.

When at least a write threshold number of encoded data slices have beensuccessfully stored, the method 1000 continues at the step 1020 wherethe processing module detects the failure of storage of an encoded dataslice. For example, the processing module determines that the writethreshold number of encoded data slices have been successfully storedbased on interpreting a received write slice responses, and identifiesthe failure of the storage of the encoded data slice based on thereceived write slice responses (e.g., a missing response, interpreting areceived response that indicates a storage error).

The method 1000 continues at the step 1030 where the processing moduledetermines whether to temporarily store the encoded data slice. Thedetermining may be based on one or more of availability of a SUassociated with the detected failure of storage, a predetermination, apriority level, a request, a lookup, and a requesting entity identifier.For example, the processing module indicates to temporarily stored theencoded data slice when determining that availability of the SUassociated with encoded data slice is unfavorable (e.g., the SU is notexpected to be available for a time frame that is greater than a maximumthreshold time level or the SU availability timing is unknown).

When temporarily storing encoded data slice, the method 1000 continuesat the step 1040 where the processing module dispersed storage errorencodes the encoded data slice to produce a set of temporary encodeddata slices. The method 1000 continues at the step 1050 where theprocessing module facilitates storage of the set of temporary encodeddata slices in a temporary storage set. The facilitating includesidentifying a storage location of the temporary storage set based on oneor more of a predetermination, interpreting a system registry, receivinga request, and identifying the temporary storage set. The facilitatingfurther includes generating a set of write slice requests that includesthe set of temporary encoded data slices and sending the set oftemporary encoded data slices to the temporary storage set.

The method 1000 continues at the step 1060 where the processing modulesubsequently determines to re-store the encoded data slice in theprimary set of SUs. The determining may include one or more of detectingthat an expiration timeframe has expired since a previous storageattempt of encoded data slice, and detecting favorable availability of aSU associated with the encoded data slice and the primary set of SUs.

The method 1000 continues at the step 1070 where the processing modulerecovers the encoded data slice from the temporary storage set. Forexample, the processing module issues read slice requests to thetemporary storage set, receives read slice responses, and dispersedstorage error decodes a decode threshold number of received temporaryencoded data slices to reproduce the encoded data slice.

The method 1000 continues at the step 1080 where the processing modulestores the encoded data slice in the primary set of SUs. For example,the processing module identifies the SU associated with the encoded dataslice, generates a write slice request that includes the reproducedencoded data slice and a slice name associated with the encoded dataslice, and sends the write slice request to the identified SU.

FIG. 11 is a diagram illustrating an embodiment of a method 1100 forexecution by one or more computing devices in accordance with thepresent invention. The method 1100 operates in step 1120 by issuing (viaan interface of a computing device that is configured to interface andcommunicate with a dispersed or distributed storage network (DSN)) a setof write requests to a first storage unit (SU) set based on a set ofencoded data slices (EDSs) associated with a data object to be storedtherein. The data object is segmented into a plurality of data segments,and a data segment of the plurality of data segments is dispersed errorencoded in accordance with dispersed error encoding parameters toproduce the set of EDSs. Also, a write threshold number of EDSs providesfor a successful transfer of the set of EDSs from a first at least onelocation in the DSN to a second at least one location in the DSN.

The method 1100 then continues in step 1120 by determining that thewrite threshold number of EDSs and fewer than all of the set of EDSshave been successfully stored within the first SUs set based on at leastsome write responses from at least some storage units (SUs) of the firstSU set. When it is unfavorably determined that the write thresholdnumber of EDSs and fewer than all of the set of EDSs have beensuccessfully stored, the method 1100 ends or alternatively operates instep 1132 by continuing to attempt/perform storage of the set of EDSsand loops back to step 1120.

Alternatively, when it is favorably determined that the write thresholdnumber of EDSs and fewer than all of the set of EDSs have beensuccessfully stored, the method 1100 continues in step 1140 bydetermining to store temporarily within a second SU set at least oneremaining EDS of the set of EDSs that has not been successfully storedwithin the first SUs set.

The method 1100 then operates in step 1150 by facilitating (e.g., viathe interface) temporary storage of the at least one remaining EDS ofthe set of EDSs within the second SU set. The method 1100 operates instep 1160 by recovering (e.g., via the interface) the at least oneremaining EDS from the temporary storage within the second SU set. Themethod 1100 then operates in step 1170 by issuing (e.g., via theinterface) at least one additional write request to the first SU setbased on the at least one remaining EDS.

This disclosure presents, among other things, various novel solutionsthat allow for a rescue of a less than complete storage process such asmade by a computing device to a set of storage units (SUs) (e.g., afirst set of SUs). For example, when a computing device sends encodeddata slices (EDSs) to a set of a width number of SUs, occasionally notall slices can be written to every SU due to availability or performancereasons. In such cases, the computing device may elect to store theseslices in a DSN memory (assuming at least a write threshold number ofslices were successfully stored). From time to time, a rebuild module,or the SU itself may check this DSN memory to see if slices have beenstored to it. If so, that entity will read the slice from the DSN memoryand store it on the SU it was destined for. Once successfullytransferred to its intended destination, it can be deleted from the DSNmemory. This eliminates the need to perform rebuilding of dropped sliceswhich is far more expensive in terms of bandwidth required. For furtherimproved security, there may be a unique vault reserved for each SU (forstoring slices intended to be stored on that SU). Optionally, the slicemay be encrypted with a key that is encrypted with a public key owned bythe intended SU, such that only the intended SU may decrypt it. Finally,rebuild modules may store slices to this storage area in the DSN memorywhen rebuilding slices known to be lost but at times the SU is offlineor is otherwise unable to receive them (e.g. due to performancereasons). This also provides flexibility to the SU to recover itsrebuilt slices at a time that is convenient and non-disruptive to normaloperations the SU may be performing at the time of the rebuild.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A computing device comprising: an interface configured to interface and communicate with a storage network; memory that stores operational instructions; and a processing module operably coupled to the interface and to the memory, wherein the processing module, when operable within the computing device based on the operational instructions, is configured to: receive a set of read slice requests for a set of encoded data slices (EDSs) associated with a data object stored within a first set of storage units, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs, wherein the storage the first set of storage units includes a first storage unit; determine whether at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units; based on a determination that at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units, identify at least one encoded data slice (EDS) associated with the data object that is stored in a second set of storage units; obtain the at least one EDS; and store the at least one EDS in the first storage unit.
 2. The computing device of claim 1, wherein a read threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the storage network to a second at least one location in the storage network.
 3. The computing device of claim 1, wherein the first set of storage units stores a first copy of the data object and the second set of storage units stores a second copy of the data object, wherein at least one EDS associated with the data object that is stored in a second set of storage units is associated with the second copy of the data object.
 4. The computing device of claim 1, wherein the determination whether at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units comprises identifying whether a storage error is associated with an encoded data slice (EDS) of the set of EDSs.
 5. The computing device of claim 4, wherein the storage error is at least one of: 1) The EDS is not found on the SU first storage unit; 2) The EDS is corrupted; 3) The EDS is unavailable; and 4) a revision number of a stored EDS does not match the read slice request for a requested EDS of the set of read slice requests.
 6. The computing device of claim 1, wherein the at least one EDS associated with the data object that is stored in a second set of storage units is identified based on at least of a system registry and a response to a query issued by the storage unit.
 7. The computing device of claim 1, wherein the at least one EDS associated with the data object that is stored in the second set of storage units is obtained by issuing a read slice request to one or more storage units of the second set of storage units.
 8. The computing device of claim 7, wherein the at least one EDS associated with the data object that is stored in the second set of storage units is obtained by receiving a read slice response from the one or more storage units of the second set of storage units.
 9. The computing device of claim 8, wherein the read slice response from the one or more storage units of the second set of storage units includes the at least one EDS.
 10. The computing device of claim 1, wherein the processing module, is further configured to: synchronize the at least one EDS with the EDSs that can be successfully retrieved from the first set of storage units.
 11. The computing device of claim 1, wherein the processing module, is further configured to: facilitate transmission of the EDSs that can be successfully retrieved from the first set of storage units along with the stored at least one EDS to another storage network entity.
 12. A method for execution by one or more processing modules of one or more computing devices of a storage network, the method comprises: receiving a set of read slice requests for a set of encoded data slices (EDSs) associated with a data object stored within a first set of storage units, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs, wherein the storage the first set of storage units includes a first storage unit; determining whether at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units; based on a determination that at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units, identifying at least one EDS associated with the data object that is stored in a second set of storage units; obtaining at least one encoded data slice (EDS); and storing the at least one EDS in the first storage unit.
 13. The method of claim 12, wherein the first set of storage units stores a first copy of the data object and the second set of storage units stores a second copy of the data object, wherein at least one EDS associated with a data object that is stored in a second set of storage units is associated with the second copy of the data object.
 14. The method of claim 12, wherein the determination whether at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of SUs comprises identifying whether a storage error is associated with an encoded data slice (EDS) of the set of EDSs.
 15. The method of claim 12, further comprising: synchronizing the at least one EDS with the EDSs that can be successfully retrieved from the first set of storage units; and facilitating transmission of the EDSs that can be successfully retrieved from the first set of storage units along with the stored at least one EDS to another storage network entity.
 16. The method of claim 12, wherein the at least one EDS associated with a data object that is stored in a second set of storage units is identified based on at least of a system registry and a response to a query issued by the computing device.
 17. The method of claim 12, wherein the at least one EDS associated with the data object that is stored in the second set of storage units is obtained by issuing a read slice request to one or more storage units of the second set of storage units.
 18. The method of claim 12, wherein the at least one EDS associated with the data object that is stored in the second set of storage units is obtained by receiving a read slice response from the one or more storage units of the second set of storage units.
 19. The method of claim 18, wherein the read slice response from the one or more storage units of the second set of storage units includes the at least one EDS associated with the data object that is stored in the second set of storage units.
 20. A non-transitory computer readable storage device comprises: a first memory section that stores operational instructions that, when executed by a computing device, causes the computing device to receive a set of read slice requests for a set of encoded data slices (EDSs) associated with a data object stored within a first set of storage units, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs, wherein the storage the first set of storage units includes a first storage unit; a second memory section that stores operational instructions that, when executed by the computing device, causes the computing device to: determine whether at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units; based on a determination that at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units, identify at least one EDS associated with the data object that is stored in a second set of storage units; obtain the at least one EDS; facilitate temporary storage of the at least one EDS in the first storage unit; synchronize the at least one EDS with the EDSs that can be successfully retrieved from the first set of storage units; and facilitate transmission of the EDSs that can be successfully retrieved from the first set of storage units along with the stored at least one EDS to another storage network entity. 